Download Neurobiology of autism

Autism spectrum disorders:
are we there yet?
 Christopher Gillberg, MD, PhD
• Canberra October 2004
Christopher Gillberg
 Professor of Child and Adolescent Psychiatry
 University of Göteborg (Queen Silvia´s
Hospital)
 University of London (St George´s Hospital
Medical School)
 University of Glasgow (Yorkhill Hospital)
 University of Bergen (Haukeland sygehus)
Autism spectrum disorders
 Diagnostic concepts and clinical
presentations
 Prevalence/incidence/epidemiology
 Acquired brain lesions and ”comorbidity”
 Genetics
 Where in the brain is autism?
 Psychosocial interactions
 Intervention
 Outcome
 The future
Diagnostic concepts and
clinical presentations
 At least four clinical presentations of autism





(autism/autistic spectrum disorder) plus ”one” nonclinical
1. Autistic disorder (Kanner syndrome) which can be
subdivided into ”low-functioning” (”Wing´s triad with
severe learning disability/MR”) and ”relatively highfunctioning”
2. Asperger’s disorder (Asperger syndrome)
3. Childhood disintegrative disorder (Heller
syndrome) - different from ”late onset autism”?
4. PDD NOS (atypical autism, other autistic-like
condition, other autism spectrum disorder)
(5. The broader autism phenotype) (lesser variant,
shadow syndrome, autistic featutres)
Prevalence, incidence/epidemiology
 Prevalence much higher than believed in the past:




ASD in 1% of population, AD in 0.2%
many studies of prevalence, very few of incidence
no good evidence that overall rates have soared
but subgroup variation likely (e.g. ”premature
autism” has gone up, ”rubella autism” down)
ASD was always quite common? - 0.7% already in
the 1970s in Sweden
–
Gillberg 1983, Gillberg & Wing 1999, Fombonne 2003
Prevalence, incidence/epidemiology
 Associated with mental retardation 15% (80% in





autistic disorder/AD)
Associated with epilepsy 5-10% (35% in AD)
Medical disorder in 10% (25% in AD)
Skewed male:female ratio 2-4:1
High rate of visual, hearing and motor
impairments (including at birth)
Sibling rate raised; identical twin rate much
raised in classic autism
–
Rutter 1971, Wing 1981, Gillberg 1983, Gillberg & Coleman 1996, Gillberg 1999, Fombonne
2003
”Acquired” brain lesions and co-existing
disorders (”medical co-morbidity”)
 Tuberous sclerosis, Fragile X syndrome, Partial
tetrasomy 15, Down syndrome, XYY, XO,
Hypomelanosis of Ito, Rett complex variants,
Angelman syndrome, Williams syndrome, CHARGE
association, Smith-Magenis syndrome, Smith-LemliOpitz syndrome, CATCH 22, Fetal alcohol syndrome,
Retinopathy of prematurity, Thalidomide
embryopathy, Valproic syndrome, Moebius syndrome,
Silver-Russell syndrome, (Landau-Kleffner
syndrome), Herpes and rubella infection
–
Gillberg & Coleman 2003
Acquired brain lesions/
medical co-morbidity
 Known medical disorders 25% in autistic
disorder ”proper” (unselected samples) and
2-10% in Asperger syndrome
 These are either genetic in their own right,
affect autism susceptibility gene areas, or
cause brain lesions through direct/indirect
insults
 High rate of pre- and perinatal risk factors
–
Gillberg & Coleman 2000
Acquired brain lesions/
medical co-morbidity
 Tuberous sclerosis
– 3-9% of all autism cases, more common in those
with epilepsy
– chromosome 16p involved in one variant (autism
susceptibility genetic area? ADHD susceptibility
genetic area)
– dopamine genes on chromosome 9 affected in
other TS variant
– autism likely if TS lesions in temporofrontal
regions and if there are many lesions
– Gillberg et al 1996, Bolton et al 1997
Acquired brain lesions/
medical co-morbidity
 Herpes encephalitis
– affects temporofrontal areas more often
than other brain structures
– can lead to classic symptoms of autism
even in previously unaffected individuals
who are 14 and 31 years of age
– Gillberg 1986, Gillberg IC 1991, Ghaziuddin et al 2002
Acquired brain lesions/
medical co-morbidity
 Thalidomide embryopathy
– Pattern of eye-abnormalities (including
Crocodile-tears) and limb anomalies in
those with autim dates the autism to 20-24
days post-conception
– 5% have classic autism (with or without
MR)
– Strömland et al 1994
Psychiatric ”co-morbidity”








ADHD/HKD (often part of autism in early life)
Tics (complex similar to stereotypies)
OCD (part of the triad?)
Anxiety (often strong environmental factors)
Depression
Bipolar disorder
Selective mutism
Most with AS will meet criteria for personaliy
disorder (inappropriate to diagnose?)
 Eating disorders (including anorexia nervosa)
 Sleep disorders
– Gillberg & Billstedt 2000
Genetics
 Sibs affected in 3%: core syndrome
 Sibs affected in 10-20%: spectrum disorder
 Identical co-twins affected in 60-90%
 Non-identical co-twins affected in 0-3%
 All of these findings refer to probands with
autism proper, not spectrum disorders
– Rutter 2002, Gillberg 2002
Genetics
 First-degree relatives increased rates of
affective disorders (including bipolar), social
phobia, obsessive-compulsive phenomena,
and ”broader phenotype symptoms”
 First-degree relatives also show possibly
increased rates of learning disorders
including MR, dyslexia and SLI
 What about ADHD? Tics?
Genetics
 Genes on certain chromosomes (e.g. 2, 6, 7,
16, 17, 18, 22, and X) may be important
(genome scan studies of sib-pairs)
 Clinical findings in particular syndromes such
as partial tetrasomy 15 (15q), Angelman
(15q), tuberous sclerosis (9q, 16p), fragile X
(X), Rett syndrome (X), Turner syndrome (X)
– Betancur 2003
Genetics
 Neuroligin genes on X-chromosome
mutated in some cases
 Neuroligin genes on other
chromosomes, including chromosome
17
 Other neurodevelopmental genes
according to microarray study
– Jamain, Bourgeron, Leboyer, Gillberg et al 2003, Laumonnier et al 2004,
Chi et al 2004, Larsson, et al 2004
Where in the brain is autism?
 Clinical finding: macrocephalus common
 Acquired brain lesions implicate fronto-
temporal and bilateral dysfunction in core
syndrome; right or left dysfunction in
spectrum disorder
 Autopsy data suggest: amygdala, pons
and cerebellum
–
Bayley et al 1997, Bauman 1988, Gillberg & Coleman 2000, Gillberg & deSouza 2002
Where in the brain is autism?
 Brainstem damage suggested by
– Thalidomide
– Moebius syndrome, CHARGE association, and
Goldenhar syndrome
– Auditory brainstem responses
– Decrease in/lack of postrotatory nystagmus
– Aberrant muscle tone and concomitant squint
– Ornitz & Ritvo 1967, Ornitz 1977, Strömland, Gillberg et al 1994, Gillberg &
Steffenburg 1997, Gillberg & Coleman 2000, Rosenhall, Gillberg et al 2003,
Johansson et al 2004
Where in the brain is autism?
Cerebellar dysfunction
suggested by
– Autopsy studies
– Imaging studies
– Relationship to ataxia
– Courchesne 1988, Bauman et al 1992, Bayley et al 1999, Oldfors, Gillberg
et al 2000, Weidenheim, Rapin, Gillberg et al 2001, Åhsgren, Gillberg et al
2004
Where in the brain is autism?
 Frontotemporal brain dysfunction
suggested by
– Autopsy studies
– Functional imaging studies
– Neuropsychological studies
– Combined neuropsychologicalneuroimaging studies
– Clinical picture
– Gillberg 1999, Gillberg 2002
Where in the brain is autism?
 Neuropsychological studies show
– Metarepresentation problems
– Aberrant reading of facial expressions
– Aberrant/unusual face processing
–
–
–
–
–
–
Non-verbal learning disability in AS
Verbal learning disability in AD
Executive function deficits
Central coherence problems
Procedural (complex) learning deficits
Superior fact learning
– Ozonoff 1994, Happé 1994, Nydén et al 2000, Baron-Cohen et al 2002,
2003, Minshew 2003, Frith 2004, Cederlund & Gillberg 2004
Where in the brain is autism?
 At least four biological variants of autism?
– Early brainstem/cerebellar associated with severe
secondary problems (and low-functioning autism
with little or no language)
– Midtrimester bitemporal lobe damage (and classic
autism with some-considerable language)
– Uni- or bilateral frontotemporal dysfunction in highfunctioning individuals (with Asperger syndrome
with good formal expressive language)
– Multi-damage autism (autism with severeprofound MR and some atypicality)
– Gillberg 2003 (Rutter lecture)
Where in the brain is autism?
 Likely that several functional neural
loops are implicated and that all
impinge on neurocognitive/social
cognitive functions that are crucially (but
possibly not specifically) impaired in
autism
–
Gillberg 1999, Gillberg & Coleman 2000
Psychopharmacology of autism
 Dopamine (Gillberg et al 1987)
 Serotonin (in MR also) (Coleman 1976)
 Noradrenaline (Gillberg et al 1987)
 Neuroligins (Jamain et al 2003)
 GFA-protein (Ahlsén et al 1993)
 Gangliosides (Nordin et al 1998)
 Endorphines (Gillberg et al 1985)
 Glycine, GABA, Ach, glutamate?
 Immune system (Plioplys 1989)
Clinical psychopharmacology of autism
 Only dopamine antagonists (old and new
neuroleptics) have been shown to affect some
core symptoms of autism in young children;
however, important side-effects, including
atypical weight-gain with risperidone; these
agents are particularly helpful for irritabledisruptive and self-injurious behaviours
 SRIs for severe OCS and anxiety
 Stimulants for severe ADHD
 Antiepileptics for epilepsy (and mood swings?)
 Peptides?? And peptide-targeted drugs?
–
Campbell et al 1976, van Buitelaar 2000, McCracken et al 2002, Lindsay & Aman
2003, Martin et al 2004, McDougle 2004
The pathogenetic chain
 Genetic or environmental insult
 Damage or neurochemical dysfunction
 Neurocognitive and social cognitive functions
restricted (procedural learning, face processing,
metarepresentations, central coherence,
executive functions)
 The ”syndrome” (or, sometimes, the
”arbitrary” symptom constellation) of autism
 The dyad (not triad) of social/communication
impairment plus the monad of restricted
behaviour pattern as a frequent concomitant?
or three monads with frequent co-existence?
Psychosocial interactions
 Not associated with social class
 Not associated with psychosocial
disadvantage; however, “pseudoautism”
described in children exposed to extreme
psychosocial deprivation
 Temporally restricted major improvement in
good psychoeducational setting
 Immigration links? Indirect link with genetic
factors?
Psychosocial interactions
 Abnormal child triggers unusual
interactions
 Some parents have autism spectrum
disorders themselves - not necessarily a
major problem in all cases
 Anxiety, violent behaviours, self-injury
and hyperactivity reduced in “autismfriendly” environment
Intervention
 All people are individuals first and foremost; at
least as true in autism as in “neurotypicality”
 People WITH autism; not autistic people!
 Change attitudes
 Respect for people in the autism spectrum
 Focus on changing environment and
 Foster adaptive skills
Intervention
 If known underlying disorder: treat this
(and be
aware of syndrome-specific symptoms such as gaze avoidance in fragile X)
 If epilepsy: treat this (however, there are
major caveats here)
 If hearing, vision, or motor impaired: treat this
 If important psychiatric co-existing problems
(SIB, ADHD, OCS, bipolar): threat these
 Psychoeducational measures
 ABA
 Symptomatic biological treatments
Intervention
 No medication for many; autism “per se” not an







agreed target for medication trials
Atypical neuroleptics (violence, self-injury, sleep
problems, hyperactivity)
antiepileptics (seizures, epileptogenic discharge?,
bipolar)
SSRIs (OCS, depression)
stimulants (ADHD)
lithium (and other drugs) for some
Other medications?
Diets??
Intervention
 Physical exercise!!
 “Sensory awareness” environment (reduce
noise, certain sounds, smell etc.)
 Autism-friendly environment
 Concrete, visual (not always), straightforward
 Minimize ambiguities and symbolic
interpretation
Outcome
 Very variable
 Poor in low- and middle-functioning cases
with AD, but quality of life very variable even
in cases with “poor” prognosis
 Better, but not always good in Asperger
syndrome
 Better with early diagnosis?
• Gillberg 1991, Nordin & Gillberg 1996, Billstedt et al 2004
Outcome
 Language at age 3 = likely later Asperger
phenotype?
 No language at age 7 = likely never much
spoken language
 Majority probably live to be old, but increased
mortality in subgroup (with medical disorders
only?)
 Basic problems remain, albeit modified
 High rate of “secondary” psychiatric problems
(personality disorder, affective, social,
catatonia)
–
Szatmari 2003, Billstedt et al 2004, Cederlund et al 2004
The future
 Specific knowledge (including genetic and
neurophysiological) and treatment for
subgroups
 New diagnostic criteria
 Symptomatic treatments
 Psychoeducation/ABA
 Acceptance and attitude change!
 People with autism, not autists or autistic
people! Cannot be stressed enough
 Respect for people with functional disabilities!
Literature
 Gillberg C & Coleman M (2000) The Biology
of the Autistic Syndromes, Third Edition.
Cambridge University Press
 Gillberg C (2002) A Guide to Asperger
Syndrome. Cambridge University Press
 Plus 300 PubMed scientific papers at
www.ncbi.nlm.nih.gov